In order to interface an integrated circuit with other circuitry, it is common to mount it on a lead frame or substrate. Each integrated circuit has bonding pads that are individually connected to the substrate's contact or terminal pads using extremely fine gold or aluminum wires or conductive balls, such as solder balls. The assemblies are then packaged by individually encapsulating them in molded plastic or ceramic bodies to create an integrated circuit package.
Integrated circuit packaging technology has seen an increase in the number of integrated circuits mounted on a single circuit board or substrate. The new packaging designs are more compact form factors, such as the physical size and shape of a packaged integrated circuit, and providing a significant increase in overall integrated circuit density.
However, integrated circuit density continues to be limited by the “real estate” available for mounting individual integrated circuits on a substrate. Even larger form factor systems, such as personal computers (PC's), compute servers, and storage servers, need more integrated circuits in the same or smaller “real estate”. Particularly acute, the needs for portable personal electronics, such as cell phones, digital cameras, music players, personal digital assistants (PDA's), and location-based devices, have further driven the need for increased integrated circuit density.
This increased integrated circuit density has led to the development of multi-chip packages in which more than one integrated circuit can be packaged. Each package provides mechanical support for the individual integrated circuits and one or more layers of interconnect lines that enable the integrated circuits to be connected electrically to surrounding circuitry.
Current multi-chip packages, also commonly referred to as multi-chip modules, typically consist of a printed circuit board (PCB) substrate onto which a set of separate integrated circuit components are directly attached. Such multi-chip packages have been found to increase integrated circuit density and miniaturization, improve signal propagation speed, reduce overall integrated circuit size and weight, improve performance, and lower costs—all primary goals of the computer industry.
Multi-chip packages whether vertically or horizontally arranged, can also present problems because they usually must be pre-assembled before the integrated circuit and integrated circuit connections can be tested. Vertically stacked integrated circuits in typical multi-chip packages can present problems beyond those of horizontally arranged integrated circuit packages, further complicating the manufacturing process. Increased input/output (I/O) density, decreased package height, and decreased cost targets all contribute to utilization of bond wires in stacked integrated circuits. These conditions increase the likelihood for wire shorting between wires connecting the various integrated circuits in the stack.
Thus, a need still remains for an integrated circuit package system providing low cost manufacturing, improved yield, and improved reliability. In view of the ever-increasing need to save costs and improve efficiencies, it is more and more critical that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.